An electric power plant generally comprises a gas turbine unit and a generator, mechanically connected to the gas turbine unit and connected to an electric distribution network. The gas turbine unit comprises a compressor, a combustion chamber and a gas turbine. Specifically, the gas turbine unit comprises a first stator element provided with first connecting holes and at least one second stator element provided with second connecting holes and connected to the first stator element.
In electric power plants of this type, maintenance operations which contemplate replacing the second stator element of the gas turbine unit with a third spare stator element sometimes need to be performed.
A known maintenance method of a gas turbine unit of an electric power plant contemplates replacing the second stator element with a third spare stator element provided with third connecting holes and coupling the first stator element to the third stator element by means of a plurality of coupling pins insertable in the first and the third connecting holes.
However, this type of technique is not effective in the very frequent cases in which the first and the third connecting holes are offset. Such offset, indeed, prevents the correct insertion of the coupling pins in the first and third connecting holes. In such case, in order to obtain the correct alignment between the first and the third connecting holes, the third spare stator element must be drilled again and the first connecting holes of the first stator element must be broadened. This technique is known as reworking the connecting holes.
However, the reworking of the first connecting holes of the first stator element cannot be performed countless times in view of the small space which is generally available by the sides of the first connecting holes. The reworking of the first connecting holes must be further performed directly on the gas turbine unit after coupling the third spare stator element to the first stator element; in most cases, on-site reworking is very burdensome, both in terms of time and in terms of costs.